Recent developments in molecular biology have generated increased interest in the genetic basis of a variety of psychiatric disorders, including alcoholism and drug dependence. The goal of this research is to identify and describe genes that have an effect on the alcoholism/drug dependence phenotype(s). We propose to probe the relationship between certain genetic polymorphisms and phenotypes related to alcoholism/drug dependence and to collect a large sample for future family-association studies useful for investigating these relationships. Genetic data will be correlated with SPECT imaging data, pharmacologic challenge data, and with other phenotypic data such as personality measures.